R. Restieri

EAQUATE: An International Experiment For Hyperspectral Atmospheric Sounding Validation

The international experiment called the European Aqua Thermodynamic Experiment (EAQUATE) was held in September 2004 in Italy and the United Kingdom to validate Aqua satellite Atmospheric Infrared Sounder (AIRS) radiance measurements and derived products with certain groundbased and airborne systems useful for validating hyperspectral satellite sounding observations. A range of flights over land and marine surfaces were conducted to coincide with overpasses of the AIRS instrument on the Earth Observing System Aqua platform. Direct radiance evaluation of AIRS using National Polar-Orbiting Operational Environmental Satellite System (NPOESS) Airborne Sounder Testbed-Interferometer (NAST-I) and the Scanning High-Resolution Infrared Sounder has shown excellent agreement. Comparisons of level-2 retrievals of temperature and water vapor from AIRS and NAST-I validated against high-quality lidar and dropsonde data show that the 1-K/l-km and 10%/1-km requirements for temperature and water vapor (respectively) are ge...

Radiometric performances of the Fourier transform spectrometer for the Radiation Explorer in the Far-Infrared (REFIR) space mission

In the framework of the Radiation Explorer in the Far InfraRed space mission for the characterization in the far infrared of the Earth outgoing emission, a breadboard version of the Fourier transform spectrometer, which is the core instrument of the payload package, has been developed. The Fourier transform spectrometer operates in the spectral range of 100-1100 cm-1 with a resolution of 0.5 cm-1, 6.5 s acquisition time, and signal-to-noise ratio better than 100. It is a compact prototype designed both for laboratory applications and for field campaigns, in particular for operations in high-altitude ground-based sites and on-board of stratospheric balloon platforms. This paper describes the instrument characterization performed in laboratory conditions and under vacuum. The study has allowed to study the trade-off among all the instrument parameters and to test the new optical design of the interferometer, with particular attention to the photolithographic beam splitters and the room-temperature pyroelectric detectors. The instrument was operated for the first time in a field campaign in June 2004 from 1247~m altitude ground-based site located in the South of Italy. The results of this test and the comparison with the measurements taken with a BOMEM spectrometer, that partially overlaps the REFIR bandwidth in the higher spectral region, are reported. Info can be found at http://radiation.ifac.cnr.it.

Aerosol optical properties variation on different mountain sites in Italy

Direct solar irradiance and IR atmospheric radiance have been measured during different measurements campaigns, conducted in three mountain sites in Italy, far from anthropogenic sources. Direct solar irradiance has been measured by a high resolution (1.5 nm) AVANTES radiometer, working in the spectral range 400 nm-900 nm, while down welling IR sky radiance measurements has been measured by an MR100 BOMEM Fourier Transform Spectrometer covering the spectral ranges 500 cm-1-5000 cm-1 and 1 cm-1 of resolution. At least two Radiosonde launches per day furnished temperature and water vapour profiles. The instruments were located on a mobile laboratory, specifically projected to host them. The parameters obtained from direct solar irradiance are Aerosol Optical Depth, Angstrom parameters and Aerosol Size Distributions retrieval, while from IR data water vapour and temperature profiles have been retrieved. Different orographic characteristics and different air-masses circulation on the measurement sites influenced Aerosol Optical Depth values and variation. Infrared radiances inversion allows the water vapour content retrieval and a correlation between aerosol effective radii and water vapour content has been looked for.

The Broadband Fourier Transform Spectrometer for the REFIR (Radiation Explorer in the Far Infrared) Space Mission

A room-temperature broadband FTS was designed for the characterization of the Earth outgoing flux in the FIR spectral range with a resolution of half wavenumber. Laboratory characterization and field measurements (ground-based and balloon) are shown.